Not all fiber optic systems are the same, and one big difference is the wavelength used for transmission. The wavelength affects performance, testing and the choice of components, so let’s see how well you understand it. Correct answers and explanations are in red.

1. The wavelength of light is basically a measure of the “color” of the light.True
False

We specify the color of light by the wavelength of the light.

2. The wavelength of light used in glass optical fiber is in a region of spectrum called _________.
A. Ultraviolet
B. Visible C. Infrared
D. Green

Fiber optic systems with glass fiber use infrared light. Visible light is in the region of 500–700nm. Infrared light is ~800nm or higher.

Connector and splice losses are not generally sensitive to the wavelength of the light.

10. When measuring optical power from a transmitter or at a receiver, the optical power meter does not need to be calibrated at the actual wavelength of the system transmitter.
TrueFalse

The detectors used in optical power meters vary greatly with wavelength, so the meter must be calibrated at the wavelength being tested. For fiber optics, meters are calibrated at 650 and 850 nm if they have silicon detectors or 850, 1300/1310 and 1550 nm for germanium or InGaAs detectors.

HAYES is a VDV writer and educator and the president of The Fiber Optic Association. Find him at www.JimHayes.com.